What does molarity measure the concentration of? a. how many isotopes of an element there are b. the number of grams in a molar mass unit c. the relative amounts of atoms in a molecule d. the amount of a substance dissolved in a liquid

1)each group 16 element has how many valence electrons? ( )4 ( )6 ( )8 ( )16 2)how many dots appear in the dot structure for calcium ion, ca2+? ( )zero ( )one ( )two ( )eight 3) which of the following atoms forms a cation to obtain an octet of outer shell electrons? ( )magnesium ( )oxygen ( )fluorine ( )helium 4) an al3+ ion contains 13 protons and 10 electrons. ( )true ( )false 5) valence and non-valence electrons are represented in lewis dot structures. ( )true ( )false

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

In pqr m< p=60 m< q= 30 and m